The present invention relates to a new transmission mechanism that allows the transformation of linear movement into circular movement and vice-versa, and may be applied to any machine in which such a transformation is required.
In piston engines, linear to rotational movement transformation is obtained by a connecting rod-crankshaft mechanism working in cooperation with pistons. As an example, and in order to provide a better technical understanding of the invention and its uses and benefits, the description below refers to use of the invention in an internal combustion engine. It may be useful to keep the following in mind with respect to the basic elements that are part of a traditional internal combustion engine, such as pistons, connecting rods and a crankshaft:
1. When explosion occurs, it acts on the piston head, generating a force directed to the connecting-rod and another lateral force that presses the piston against the cylinder wall, which creates energy losses due to friction and tends to wear the cylinder into an oval shape. This frictional force reaches its maximum value immediately after the explosion, thus causing the sliding of these surfaces to occur under extreme lubricating conditions and at very high temperature, pressure and speed. PA1 2. When the piston reaches both maximum points in its stroke, there is an abrupt inversion of movement. This acts negatively on the performance of the engine in direct proportion to the speed and mass of the group formed by the piston, piston rings, pin and one third of the connecting rod. PA1 3. For a given cylinder volume and rpm, the torque, piston speed, and thermal performance may change as a function of the relationship between the length of the connecting rod, the piston diameter and the crankweb. Based on past experience, a "square piston" or "super square" configuration has been generalized as the preferred alternative. It is generally accepted that the efficiency depending on these three elements (connecting rod, piston and crankshaft) has reached a maximum that cannot be surpassed. Moreover, it is well known that these three elements have not undergone important changes for many years. All the advances in the performance of engines have been due to innovations in other parts of the engines (intake, valves, carburation, ignition, camshaft, distribution, etc.)
The three preceding paragraphs describe negative conditions which comprise the efficiency of an engine, and which are, among others, very well known by those skilled in the art. Several solutions have been proposed attempting to solve the problems that have been found. Among them, the Wankel rotating engine, with its over forty years of experimentation, has had limited success, but it cannot compete with the conventional engine.
The present invention utilizes the crankshaft-connecting rod-piston assembly, which are the elements that have undergone the fewest improvements, if any, in the past years. This obviously bestows on the present invention a particular importance because, far from attempting to alter all the technical evolution of other engine parts, it cooperates with them and even makes it possible to enhance their respective efficiencies.
The mechanism of the present invention comprises an assembly formed by a crankshaft having a rotatable member mounted on the crankshaft elbow. The member is shaped as two partially juxtaposed grooved wheels, one behind the other, in such a way that their geometric axes do not coincide. These axes are separated and, between both and equally distant from each other, is the turning axis that corresponds to the elbow axis. The three axes (the elbow axis and each of the wheel axes) are parallel and are on the same front-back plane. When the member rotates on the elbow, each of the wheels behaves as an eccentric, thus providing a front eccentric wheel and a rear eccentric wheel.
On the front eccentric wheel there are two bearing-mounted connecting rods with their distal ends forming the shape of a piston with no joint in between, each connecting rod being an integral piece with its own piston. The connecting rods are split-head connecting rods with the unique feature that each one has only one half of its head and is connected to the half-head of the other connecting rod by means of groove pins similar to conventional ones. In this way a pair of connecting rods opposed to each other is obtained whose longitudinal axes are common and coincident with the axis of the corresponding opposite cylinder.
On the front face of the head of this double connecting rod, an internally cogged gear or crown is attached and properly positioned. The center and the front-back axis of the crown coincide with the corresponding center and axis of the connecting rod bearing. The crown is divided into two halves, each one of which remains mounted on a corresponding connecting rod if they are separated. The crown tangentially engages the crankshaft elbow and this elbow has a gear found on or connected to the contacting segment so that as the crankshaft rotates, the gear on the elbow behaves as a satellite to the crown. The number of cogs on the crown is double that of the satellite gear.
Forming part of the connecting rod head and on opposite poles there are two planes parallel to the axis of the pistons. These planes slide between two roller holder plates, which are opposed to each other and attached to the fixed structure of the engine so as to form a channel. Inside of this channel the head of the connecting rod slides as the crankshaft turns. A similar assembly is mounted on the rear eccentric wheel, except that it does not have a crown or gear.
Therefore, one embodiment of the present invention includes an engine with two pairs of opposite cylinders and a special feature, which is completely new, allowing the movement of the connecting rods to be purely linear rather than oscillating. Another new feature is that the pair of cylinders is perpendicular one to the other in such a way that when the front connecting rods move horizontally, the rear ones move vertically. This mechanism also makes the force acting on the crankshaft elbow double in intensity compared to the expansion force.
If necessary, many assemblies can be mounted one after the other along the crankshaft in order to meet the special conditions and requirements needed for each engine. The best functional balance is obtained when four pairs of cylinders or more are used.
In conventional internal combustion engines, the inertia of the piston (the speed of which may, according to the run and rpm of the engine, reach or surpass 15 m/sec), and the many high speed movement inversions of the piston, rings, pin and connecting rod assembly, negatively effect engine operation. These effects increase mechanical losses, produce strong vibrations and intensify the friction effect of the piston against the cylinder, increasing the wear of both elements. The mechanism of the present invention minimizes these effects, mainly because there are no lateral forces of the pistons against the cylinder walls. The pistons slide inside the cylinders without theoretically making contact with them; only the rings do in their sealing function. The piston and cylinder oil gap is kept constant along the entire perimeter and at all times. This enhances the engine thermal efficiency since the engine can work at higher temperatures without the risk of the piston getting stuck inside the cylinder, as the absence of friction lowers this risk dramatically.
Due to the lack of oscillating movement of the connecting rod and the lack of lateral force of the pistons, these components do not have a tendency to pitch. This allows the piston length to be not greater than the strictly necessary one for holding the rings. The reduction in the piston length, the short length of the connecting rods, the light weight alloy they may be made of and the absence of a connecting pin help to increase the mechanical efficiency because of a reduction of mass. It is important to emphasize that each connecting rod and its piston forms a single piece. Because of the above-mentioned reductions in size, the cylinders are short. The distance from the crankshaft longitudinal axis to the cylinder-head union is not bigger than half the distance of traditional ones. The crankshaft length is also reduced and is less than half the length of traditional ones, so that its resistance to torsion shows a comparatively remarkable increase. With the proposed mechanism, the need for cooling decreases and consequently the cooling system is smaller.
In light of the foregoing description, it may be easily verified that an engine with smaller size and weight may be obtained when using the present invention. This, and the functional advantages mentioned above, confirm that the weight/power relation of the present invention is highly advantageous when applied to internal combustion engines, and compared to conventional ones. It is an object of the invention to provide an improved mechanism for movement transmission in piston engines, mainly in the transformation of linear to rotary movement therein.
For a better understanding of the present invention, a preferred embodiment of the invention will be described (as an illustrative example only and not as a limitation on the invention's scope), making reference to the attached drawings which show the essential parts of the invention.